• Journal of Korean Society for Quality Management
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• v.14 no.2
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• pp.40-46
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• 1986

The decision maker has the job of torecasting capital investments and operating expenses to aid the decision making in choosing and evaluating present and future alternatives. The estimating function eventually analysis, evaluates and choose the alternatives. The analysis stemmed originally from a preliminary design of some sort, and eventually plans are started to investigate investment possibilites. This study provide the descounted cash flow and the present worth method. Despite any choice of an analytical method, there remains the problem of predicting certain future events. Therefore, these models dealing with optimum plant sizing, equipment replacement, and lease or buy will be discussed.

• Computers and Concrete
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• v.23 no.3
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• pp.161-170
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• 2019

This paper aims at presenting a numerical method for estimating the elastic modulus of recycled concrete with crushed aggregates. In the method, polygonal aggregates following a given sieve curve are generated, and placed into a square simulation element with the aid of the periodic boundary condition and the overlap criterion of two polygonal aggregates. The mesostructure of recycled concrete is reconstructed by embedding an old interfacial transition zone (ITZ) layer inside each recycled aggregate and by coating all the aggregates with a new ITZ layer. The square simulation element is discretized into a regular grid and a representative point is selected from each sub-element. The iterative method is combined with the fast Fourier transform to evaluate the elastic modulus of recycled concrete. After the validity of the numerical method is verified with experimental results, a sensitivity analysis is conducted to evaluate the effects of key factors on the elastic modulus of recycled concrete. Numerical results show that the elastic modulus of recycled concrete increases with the increase of the total aggregate content and the elastic moduli of old and new ITZ but decreases with increasing the replacement ratio of recycled aggregate and the thicknesses of old and new ITZ. It is also shown that, for a replacement ratio of recycled aggregate smaller than 0.3, the elastic modulus of recycled concrete is reduced by no more than 10%.

• The Journal of Fisheries Business Administration
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• v.54 no.2
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• pp.1-14
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• 2023

The sustainability of fishing villages is threatened by manpower shortages due to population aging and poor settlement conditions. In the reality of poor fishing villages, the importance of women's labor is more emphasized than that of the past because female workers are key workers in fishing labor, processing and sales of marine products. However, policy support for female fishermen is not sufficient. The reason for this is that policy makers did not properly recognize the labor value of female fishermen. In fact, fishing villages have emphasized the importance of female workforce as a slogan, but there has been no attempt to estimate the labor value. There was not even a review of the methodology for estimating the value of labor that was attempted in similar fields. As a result, the policy importance of female fishermen was underestimated for there was no attempt to evaluate their value even though women had been continuously participating in the fishery from the past. Female fishermen's labor is under the dual labor structure of housework and fishing labor. Therefore, in this study, housework and fishing labor were estimated separately and the total labor value was calculated. The basic data necessary for estimating the labor value of female fishermen were obtained through a survey. The method of estimating the labor value of female fishermen was used in combination with the present income method and the total replacement cost method. As a result of the study, the total labor value of female fishermen was about 4.4 trillion won, which is about half of the total fishery production of 9 trillion won in Korea.

• Journal of Chest Surgery
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• v.32 no.4
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• pp.373-378
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• 1999

Background: Minimally invasive technique for various cardiac surgeries has become widely accepted since it has been proven to have distinct advantages for the patients. We describe here the results of our experiences of minimal incision in cardiac surgery. Material and Method: From February 1997 to November 1998, we successfully performed 31 cases of minimally invasive cardiac surgery. Male and female ratio was 17:14, and the patients age ranged from 1 to 75 years. A left parasternal incision was used in 9 patients with single vessel coronary heart disease. A direct coronary bypass grafting was done under the condition of the beating heart without cardiopulmonary bypass support(MIDCAB). Among these, one was a case of a reoperation 1 week after the first operation due to a kinked mammary artery graft. A right parasternal incision was used in one case of a redo mitral valve replacement. Mini-sternotomy was used in the remaining 21 patients. The procedures were mitral valve replacement and tricuspid annuloplasty in 6 patients, mitral valve replacement 5, double valve replacement 2, aortic valve replacement 1, removal of left atrial myxoma 1, closure of atrial septal defect 2, repair of ventricular septal defect 2, and primary closure of r ght ventricular stab wound 1. The initial 5 cases underwent a T-shaped mini-sternotomy, however, we adopted an arrow-shaped ministernotomy in the remaining cases because it provided better exposure of the aortic root and stability of the sternum after a sternal wiring. Result: The operation time, the cardiopulmonary bypass time, the aorta cross-clamping time, the mechanical ventilation time, the amount of chest tube drainage until POD#1, the chest tube indwelling time, and the duration of intensive care unit staying were in an acceptable range. There were two surgical mortalities. One was due to a rupture of the aorta cannulation site after double valve replacement on POD#1 in the mini-sternotomy case, and the other was due to a sudden ventricular arrhythmia after MIDCAB on POD#2 in the parasternal incision case. Postoperative complications were observed in 2 cases in which a cerebral embolism developed on POD#2 after a mini-sternotomy in mitral valve replacement and wound hematoma developed after a right parasternal incision in a single coronary bypass grafting. Neither mortality nor complication was directly related to the incision technique itself. Conclusion: Minimally invasive surgery using parasternal or mini-sternotomy incision can be used in cardiac surgeries since it is as safe as the standard full sternotomy incisions.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.16-24
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• 2018

In this study, an experiment was conducted to analyze mortar based rheology for 3D printing method application. The tendency of rheological properties due to the change of W/B, binder type, replacement ratio, and super plasticizer which have a great influence on the flow characteristics of concrete was experimentally analyzed. Experiments were carried out by dividing into paste and mortar. In the paste experiment, rheology was analyzed by setting W/B, binder type, replacement ratio, and super plasticizer dosage as main variables. In the mortar experiment, the rheological properties of W/B and sand ratio were analyzed. As a result, as the W/B was increased, the viscosity decreased and the FA ratio to replace FA increased and the viscosity increased. In order to increase the fluidity, substitution of only 5% of SF reduces the shear stress and the viscosity is reduced by about 83%. Mortar rheological evaluation shows that there is a critical section where a large change occurs in the W/B 30 to 40% section. Also, in the same W/B, it is analyzed that there is a critical section where the shear stress increases more than twice in the sand ratio of 50~60%.

• Journal of Chest Surgery
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• v.35 no.8
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• pp.584-589
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• 2002

Background : The thoracic and thoracoabdominal aortic surgery is a complicated procedure that has various method of approach and protection. The authors have performed several methods to treat these diseases. Therefore, we attempt to analyze their results and risks. Material and Method: From June of 1992 to August of 2001, we performed 26 cases of thoracic aortic surgery and 10 cases of thoracoabdominal aortic surgery. There were 17 aortic dissections, 17 aortic aneurysms, one coarctation of aorta and one traumatic aortic aneurysm. The thoracic aortic replacement was performed under a femorofemoral bypass, an LA to femoral bypass, or a deep hypothermic circulatory arrest. The thoracoabdominal aortic replacement was performed under a femorofemoral bypass or a pump assisted rapid infusion. Result: There were 7 renal failures, 11 hepatopathies, 7 cerebral vascular accidents, 2 heart failures, 5 respiratory insufficiencies, and 2 sepsis in postoperative period. There were 9 hospital mortalities which were from 2 bleedings, 2 heart failures, 2 renal failures, a sepsis, a respiratory failure, and a cerebral infarction. There were 3 late deaths which were from ruptured distal anastomosis, cerebral infarction, and pneumonia. Conclusion: Deep hypothermic circulatory arrest was not good supportive methods for thoracic aortic replacement. Total thoracoabdominal aortic replacement was a high risk operation.

• Journal of Korea Water Resources Association
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• v.42 no.7
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• pp.525-535
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• 2009

In this paper a heuristic method for identifying individual pipes in water pipe networks to determine specific sections of the pipes that need to be replaced due to deterioration. An appropriate minimum pipe length is determined by selecting the pipe length that has the greatest variance of the average cumulative break number slopes among the various pipe lengths used. As a result, the minimum pipe length for the case study water network is determined as 4 m and a total of 39 individual pipe IDs are obtained. The economically optimal replacement times of the individual pipe IDs are estimated by using the threshold break rate of an individual pipe ID and the pipe break trends models for which the General Pipe Break Prediction Model(Park and Loganathan, 2002) that can incorporate the linear, exponential, and in-between of the linear and exponetial failure trends and the ROCOFs based on the modified time scale(Park et al., 2007) are used. The maximum log-likelihoods of the log-linear ROCOF and Weibull ROCOF estimated for the break data of a pipe are compared and the ROCOF that has a greater likelihood is selected for the pipe of interest. The effects of the social costs of a pipe break on the optimal replacement time are also discussed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.235-244
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• 2020

This study conducted a series of studies to offer a novel method of using CBS-dust that produced as by-product in the manufacture of cement. Four different contents of BS and CBS-dust were adopted for test parameters of this study. Mortar with 50% of W/B was fabricated. First, in the case of the fresh mortar, the flow decreased as the CBS-dust replacement rate increased, but the binder composition ratio BS 45% and 65% showed higher fl ow than Pl ain when repl acing CBS-dust 5%. In the case of air content, overall, the tendency was proportional to the CBS-dust replacement rate, and chloride tended to exceed the reference value at all replacement rates except for the CBS-dust 0% replacement. The compressive strength of the hardened mortar shows the resul t that the strength is improved when the CBS-dust is repl aced by 5% to 10%, and the CSH gel and structure formation is confirmed by microstructure analysis through the hydration reaction when the CBS-dust is replaced. Therefore, for a given condition CBS-dust is used as a early-strength admixture in a concrete secondary product that uses a large amount of admixture without reinforcing bars it can be an effective method for enhancing the strength of concrete as an alkali activator.

• Journal of Chest Surgery
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• v.32 no.3
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• pp.262-269
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• 1999

Background: To review the middle and long term results of aortic valve replacement(AVR) for 11 years, we surveyed and followed up the patients who underwent AVR. Material and Method: Between Feb. 1986 and May 1997, 134 patients underwent AVR. The patients consisted of 71 men and 63 women whose mean age was 38.9 years, ranging from 17 to 70. Result: The concomitant operations were 62 mitral valve replacement(MVR), 14 MVR + tricuspid valve annuloplasty, 10 Cabrol operation, 16 aortic annulus widening, and so forth. We used 119 mechanical(75 St. Jude Medical, 38 CarboMedics, 6 Sorin) and 15 tissue (Carpentier-Edwards) valves. Early postoperative complications occurred in 35 cases; 9 congestive heart failure, 6 low cardiac output, 5 postoperative bleeding, 5 pleural effusion, and so forth. There were 13 early postoperative deaths(9.7%) due to low cardiac output(5), CHF (2), disseminated intravascular coagulopathy(2), and so forth. The cumulative total follow-up period was 452.7 patient-years with a mean of 3.4${\pm}$3.1 years/patient. There were 9 cases of valve-related complications; anticoagulant-related bleeding(4), prosthetic valve endocarditis(2), thromboembolism(2) and prosthetic valve failure(1) occured at rate of 0.9, 0.4, 0.4, 0.2%/ pt-yr, respectively. Late valve-related death occurred in 3 cases(2.0%/pt-yr) associated with anticoagulant-related bleeding(2) and prosthetic valve endocarditis(1). Conclusion: Actuarial survival rate by Kaplan-Meier method was 91.0${\pm}$4.3 % at 11 years.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.1-10
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• 2010

Recently heterogeneous storage system such as hybrid hard disk drive (H-HDD) combining flash memory and magnetic disk is launched, according as the read performance of NAND flash memory is enhanced as similar to that of hard disk drive (HDD) and the power consumption of NAND flash memory is reduced less than that of HDD. However, the read and write operations of NAND flash memory are slower than those of rotational disk. Besides, serious overheads are incurred on CPU and main memory in the case that intensive write requests to flash memory are repeatedly occurred. In this paper, we propose the Least Frequently Used-Hot scheme that replaces the data blocks whose reference frequency of read operation is low and update frequency of write operation is high, and the data flushing scheme that rearranges the data blocks into the multi-zone of the rotation disk. Experimental results show that the execution time of the proposed method is 38% faster than those of conventional LRU and LFU block replacement schemes in I/O performance aspect and the proposed method increases the life span of Non-Volatile Cache 40% higher than those of conventional LRU, LFU, FIFO block replacement schemes.